1. Technical Field of the Invention
The present invention relates to a webbing take-up device for use in a seat belt apparatus for protecting a vehicle occupant in the event of a vehicular emergency, in which an ELR mode and an ALR mode can be properly switched. In the ELR mode, an ELR prevents a take-up shaft from rotating in the direction in which the webbing is unwound, only in the event of a vehicular emergency. In the ALR mode, an ALR always prevents the webbing from being unwound, after a predetermined amount of the webbing has been unwound.
2. Description of the Related Art
In a webbing take-up device with which a vehicle is equipped, there is provided a locking mechanism for, when necessary, preventing the webbing from being unwound.
The locking mechanism comprises an ELR (i.e., Emergency Locking Retractor) and an ALR (i.e., Automatic Locking Retractor). Ordinarily, taking-up and unwinding (pulling-out) of the webbing is possible. In the event of a vehicular emergency, the ELR detects the state of emergency by an acceleration detection means and instantaneously prevents a take-up shaft from rotating in the direction in which the webbing is unwound. The ALR continually prevents further unwinding of the webbing after a predetermined amount of the webbing has been unwound.
In the ELR, a locking wheel is provided so as to follow the rotation of the take-up shaft in the direction in which the webbing is unwound, and an elastic body is inserted between the locking wheel and the take-up shaft. Therefore, in a normal state, the locking wheel and the take-up shaft integrally rotate. As a result, since it is possible to freely take up or unwind the webbing from the take-up shaft when the vehicle is in a state of normal travelling, a vehicle occupant can freely change his or her posture. In the event of vehicular emergency, an acceleration detection means prevents the locking wheel from rotating, and, due to the delayed rotation of the locking wheel relative to the take-up shaft, a locking member which rotates with the take-up shaft is guided and moved to mesh with ratchet teeth of a frame. As a result, the take-up shaft is prevented from rotating so that the webbing is stopped from unwinding.
On the other hand, in the ALR, an ALR pawl prevents the locking wheel from rotating due to unwinding of the webbing in a predetermined amount (therefore, in this state, the locking member which rotates together with the take-up shaft meshes with the ratchet teeth of the frame), and, thereafter, further unwinding of the webbing from the take-up shaft is not allowed so that the vehicle occupant can be securely restrained.
A webbing take-up device in which the ELR and the ALR are jointly provided has already been proposed by the same applicant of the present invention (for example, Japanese Patent Application Laid-Open (JP-A) No. 10-244905, Japanese Utility Model Application Publication (JP-Y) No. 7-47239, and the like).
In a webbing take-up device of this type, the ELR and ALR can be switched as needed. That is, when the webbing take-up device is between a state in which an entire amount of the webbing has been taken up by the take-up shaft and a state in which a predetermined amount of the webbing has been unwound, an ALR lever which is allowed to engage with the locking wheel by means of an urging force is compellingly disengaged from the locking wheel, and further engagement is prevented, and the locking member is controlled by the acceleration detecting means (that is, the ELR operative state). On the other hand, when the webbing take-up device is in a state in which a predetermined amount of the webbing has been unwound (for example, an entire amount of the webbing has been unwound), the ALR lever is compellingly engaged with the locking wheel so as to prevent further unwinding of the webbing (that is, the ALR operative state).
Accordingly, a single webbing take-up device is able to function as either the ELR or the ALR, according to the situation.
In a webbing take-up device of this type, there has been a drawback in that, in a state in which both taking up and unwinding of the webbing are possible (namely, in the ELR state), when a vehicle occupant to whom the webbing has been harnessed stoops or the like, the webbing take-up device may unintendedly and unnecessarily be switched to a state in which the webbing is prevented from unwinding (namely, the ALR state), which may make the vehicle occupant feel unpleasant.
In this case, it is possible to conceive of setting the overall length of the webbing to be much longer than the length required for ordinary use to harness the vehicle occupant, so that unnecessary switching from the ELR mode to the ALR mode may be prevented. However, simply setting the overall length of the webbing to be long may lead to increases in the size and cost of the device.
In view of the aforementioned, it is an object of the present invention to provide a webbing take-up device in which unintended and unnecessary switching from an ELR mode to an ALR mode can be prevented.
In accordance with a first aspect of the present invention, here is provided a webbing take-up device which operates in one of an ELR mode in which, in only a case of a vehicular emergency, a rotating of a take-up shaft of a webbing in a direction in which the webbing is unwound is prevented, and an ALR mode in which, after a predetermined amount of the webbing is unwound, an unwinding of the webbing is always prevented, wherein: a switching from the ELR mode to the ALR mode is carried out by, in the ELR mode, unwinding an entire amount of the webbing; taking up a predetermined amount of the webbing from a state in which the entire amount of the webbing is unwound; unwinding the entire amount of the webbing from a state in which the predetermined amount of the webbing is taken-up; and taking up the predetermined amount of the webbing from the state in which the entire amount of the webbing is unwound, in serial order; and a switching from the ALR mode to the ELR mode is obtained by, in the ALR mode, taking up a predetermined amount of the webbing.
In accordance with a second aspect of the present invention, there is provided a webbing take-up device comprising: a take-up shaft which takes up a webbing for restraining a vehicle occupant; a locking device which can engage with the take-up shaft to prevent the take-up shaft from rotating in a direction in which the webbing is unwound; a locking wheel which following rotates around the take-up shaft, and, when stops rotating, which guides the locking device such that the take-up shaft is prevented from rotating; an acceleration detecting means which detects a state of a vehicle emergency, and which stops the locking wheel from rotating; an ALR pawl which is able to move so as to switch between a state in which the ALR pawl engages with the locking wheel so as to prevent the locking wheel from rotating, and a state in which the ALR pawl is spaced from the locking wheel so as to allow the locking wheel to rotate; a reduction mechanism which operates due to an intermittent motion, comprising a driving gear which rotates integrally with the take-up shaft and a reduction gear which meshes with the driving gear; a disc control member which is provided with a braking operational portion which engages with the ALR pawl so as to keep the ALR pawl spaced from the locking wheel, and an intermediate holding surface which is disposed adjacent to the braking operational portion and which engages with the ALR pawl so as to keep the ALR pawl spaced from the locking wheel; and a cam member which is rotated by the reduction mechanism in an interlocking manner, and which is provided with a first pressing surface and a second pressing surface for pressing the disc control member, and which engages with the ALR pawl so as to keep the ALR pawl spaced from the locking wheel, wherein the webbing take-up device operates in one of an ELR mode or an ALR mode, the switching between the ELR mode or the ALR mode being carried out by the ALR pawl which is switched between a state in which the ALR pawl prevents the locking wheel from rotating, and a state in which the ALR pawl allows the locking wheel to rotate, wherein switching from the ELR mode to said ALR mode is carried out in a manner that: in the ELR mode, when an entire amount of the webbing, which is taken up by the take-up shaft, is unwound, the braking operational portion of the disc control member is disposed so as to keep the ALR pawl spaced from the locking wheel; and the disc control member and the cam member are disposed such that the first pressing surface of the cam member which is interlocked by the take-up shaft presses and rotates the disc control member, and that the ALR pawl is moved from the braking operational portion to be placed on the intermediate holding surface; when the entire amount of the webbing is unwound again after a predetermined amount of the webbing, the entire amount of which is unwound, is taken up, the disc control member and the cam member are disposed such that the second pressing surface of the cam member which is interlocked by with the take-up shaft presses and rotates the disc control member, and that the ALR pawl is moved from the intermediate holding surface to be placed on the cam member, and when the webbing, the entire amount of which is unwound, is taken up again, the ALR pawl engages with the locking wheel in such a manner in which the cam member which is interlocked by the take-up shaft rotates to be separated from the ALR pawl, and wherein a switching from the ALR mode to said ELR mode is carried out in a manner that: in said ALR mode, when a predetermined amount of the webbing is taken up, the braking operational portion keeps the ALR pawl spaced from the locking wheel in a manner that the cam member presses and rotates the disc control member.
In accordance with a third aspect of the present invention, there is provided a webbing take-up device comprising: a take-up shaft which takes up a webbing for restraining a vehicle occupant; a locking device which can engage with the take-up shaft to prevent the take-up shaft from rotating in a direction in which the webbing is unwound; a locking wheel which following rotates around the take-up shaft, and, when stops rotating, which guides the locking device such that the take-up shaft is prevented from rotating; an acceleration detecting means which detects a state of a vehicle emergency, and which stops the locking wheel from rotating; an ALR pawl which is able to move so as to switch between a state in which the ALR pawl engages with the locking wheel so as to prevent the locking wheel from rotating, and a state in which the ALR pawl is spaced from the locking wheel so as to allow the locking wheel to rotate, and which is integrally provided with a assistant arm; a switching holding member which holds the ALR pawl in one of a state in which the locking wheel is prevented from rotating, and a state in which the locking wheel is allowed to rotate; and a cam member which is rotated by the take-up shaft in a interlocking manner, and which is provided with a first protrusion, which engages with the ALR pawl to prevent the locking wheel from rotating, and a second protrusion, which engages with the ALR pawl to keep the ALR pawl spaced from the locking wheel, and in which a guide groove for guiding the assistant arm is formed, wherein the webbing take-up device operates in one of an ELR mode or an ALR mode, the switching between the ELR mode or the ALR mode thereof being carried out by the ALR pawl which is switched between a state in which the ALR pawl prevents the locking wheel from rotating, and a state in which the ALR pawl allows the locking wheel to rotate, wherein switching from the ELR mode to the ALR mode is carried out in a manner that: in the ELR mode, when an entire amount of the webbing, which is taken up by the take-up shaft, is unwound, the cam member is disposed in a manner in which the first protrusion of the cam member which is interlocked by the take-up shaft presses and rotates the ALR pawl so that the assistant arm of the ALR pawl abuts against the cam member and the ALR pawl is spaced from the locking wheel, when the entire amount of the webbing is unwound again after a predetermined amount of the webbing, the entire amount of which is unwound, is taken up, the cam member is disposed so as to allow the assistant arm to enter the guide groove of the cam member, and when the webbing, the entire amount of which is unwound, is taken up again, the cam member is disposed in a manner that the cam member which is interlocked by the take-up shaft rotates and the assistant arm enters the guide groove so that the ALR pawl rotates to engage with the locking wheel, and wherein a switching from the ALR mode to the ELR mode is carried out in a manner that: in the ALR mode, when a predetermined amount of the webbing is taken up, the second protrusion of the cam member which is rotated presses and rotates the ALR pawl to have the ALR pawl spaced from the locking wheel.
In accordance with a fourth aspect of the present invention, there is provided a webbing take-up device comprising: a take-up shaft which takes up a webbing for restraining a vehicle occupant; a locking device which can engage with the take-up shaft to prevent the take-up shaft from rotating in a direction in which the webbing is unwound; a locking wheel which following rotates around the take-up shaft, and, when stops rotating, which guides the locking device such that the take-up shaft is prevented from rotating; an acceleration detecting means which detects a state of a vehicle emergency, and which stops the locking wheel from rotating; an ALR pawl which is able to move so as to switch between a state in which the ALR pawl engages with the locking wheel so as to prevent the locking wheel from rotating, and a state in which the ALR pawl is spaced from the locking wheel so as to allow the locking wheel to rotate; a reduction mechanism which operates due to an intermittent motion, comprising a driving gear which rotates integrally with the take-up shaft and a reduction gear which meshes with the driving gear; a disc control member which is provided with a braking operational portion which engages with the ALR pawl so as to keep the ALR pawl spaced from the locking wheel, and which is provided with a guide pin; and a cam member which is rotated by the reduction mechanism in an interlocking manner, and which is provided with a guide groove which guides the guide pin which has entered therein and which is able to press the guide pin at least two predetermined end portions thereof, and which engages the ALR pawl so as to keep the ALR pawl spaced from the locking wheel, wherein the webbing take-up device operates in one of an ELR mode or an ALR mode, the switching between the ELR mode or the ALR mode being carried out by the ALR pawl which is switched between a state in which the ALR pawl prevents the locking wheel from rotating, and a state in which the ALR pawl allows the locking wheel to rotate, wherein switching from the ELR mode to the ALR mode is carried out in a manner that: in the ELR mode, when an entire amount of the webbing, which is taken up by the take-up shaft, is unwound, the braking operational portion of the disc control member is disposed so as to keep the ALR pawl spaced from the locking wheel; when the entire amount of the webbing is unwound again after a predetermined amount of the webbing, the entire amount of which is unwound, is taken up, the disc control member and the cam member are disposed such that an one predetermined end portion of the predetermined end portions of the guide groove of the cam member which is interlocked by the take-up shaft presses the guide pin to rotate the disc control member so that the ALR pawl is moved from the braking operational portion to be placed on the cam member, and when the webbing, the entire amount of which is unwound, is taken up again, the ALR pawl engages with the locking wheel in such a manner in which the cam member which is interlocked by the take-up shaft rotates to be separated from the ALR pawl, and wherein a switching from the ALR mode to the ELR mode is carried out in a manner that: in the ALR mode, when a predetermined amount of the webbing is taken up, an another predetermined end portion of the predetermined end portions of the guide groove of the cam member which is rotated presses the guide pin to rotate the disc control member so that the braking operational portion keeps the ALR pawl spaced from the locking wheel.
In accordance with a fifth aspect of the present invention, there is provided a webbing take-up device which operates in one of an ELR mode in which, in a case of a vehicular emergency, a rotating of a take-up shaft of a webbing in a direction in which the webbing is unwound is prevented, and an ALR mode in which, after a predetermined amount of the webbing is unwound, an unwinding of the webbing is prevented, wherein: a switching from the ELR mode to the ALR mode is carried out by, in the ELR mode, a combination action of unwinding an entire amount of the webbing and taking up a predetermined amount of the webbing from a state in which the entire amount of the webbing is unwound.
In accordance with a sixth aspect of the present invention according to the fifth aspect, wherein a switching from the ALR mode to the ELR mode is obtained by, in the ALR mode, taking up a predetermined amount of the webbing.
In the webbing take-up device according to the first aspect of the present invention, the switching from the ELR mode to the ALR mode is achieved by conducting the respective unwinding and taking-up operations of the webbing twice in sequential order. Accordingly, unless the aforementioned switching is carried out by the conscious volition of the vehicle occupant, an unintended and unnecessary switching from the ELR mode to the ALR mode which may make the vehicle occupant feel unpleasant does not happen.
Further, as a result, it is not necessary to set the overall length of the webbing to be much longer than the length ordinarily required to harness the vehicle occupant. Therefore, increases in size and cost can be avoided.
In the webbing take-up device according to the second aspect of the present invention, when the webbing take-up device is switched from the ELR mode to the ALR mode, by unwinding an entire amount of the webbing, the first pressing surface of the cam member presses and rotates the disc control so as to move the ALR pawl from the braking operational portion to be placed on the intermediate holding surface. Further, from this state in which the entire amount of the webbing has been unwound, by unwinding the entire amount of the webbing again after taking up a predetermined amount of the webbing, the second pressing surface of the cam member again presses and rotates the disc control so as to move the ALR pawl from the intermediate holding surface to be placed on the cam member. Then, from this state in which an entire amount of the webbing is unwound, by taking up the webbing again, the webbing take-up device is switched to the ALR mode where the cam member rotates to be disengaged from the ALR pawl and then the ALR pawl engages with the locking wheel to prevent the locking wheel from rotating.
In the webbing take-up device according to the second aspect of the present invention, the switching from the ELR mode to the ALR mode is achieved by conducting the respective unwinding and taking-up operations of the webbing twice in sequential order. Accordingly, unless the aforementioned switching is carried out by the conscious volition of the vehicle occupant, an unintended and unnecessary switching from the ELR mode to the ALR mode which may make the vehicle occupant feel unpleasant does not happen.
Further, as a result, it is not necessary to set the overall length of the webbing to be much longer than the length ordinarily required to harness the vehicle occupant. Therefore, increases in size and cost can be avoided.
In the webbing take-up device according to the third aspect of the present invention, when the webbing take-up device is to be switched from the ELR mode to the ALR mode, by unwinding an entire amount of the webbing, the first protrusion of the cam member presses and rotates the ALR pawl such that the assistant (auxiliary) arm of the ALR pawl abuts against the cam member, and that the ALR pawl is disengaged from the locking wheel. Further, from this state in which the entire amount of the webbing has been unwound, by taking up a predetermined amount of the webbing, the cam member is disposed at a position where the assistant arm is able to enter the guide groove of the cam member. Also, after that, by unwinding the entire amount of the webbing again, the cam member rotates so that the assistant arm enters the guide groove and the ALR pawl then rotates to engage with the locking wheel. As a result, the switching to the ALR mode is carried out.
In the webbing take-up device according to the third aspect of the present invention, the switching from the ELR mode to the ALR mode is achieved by conducting the respective unwinding and taking-up operations of the webbing twice in sequential order. Accordingly, unless the aforementioned switching is carried out by the conscious volition of the vehicle occupant, an unintended and unnecessary switching from the ELR mode to the ALR mode which may make the vehicle occupant feel unpleasant does not happen.
Further, as a result, it is not necessary to set the overall length of the webbing to be much longer than the length ordinarily required to harness the vehicle occupant. Therefore, increases in size and cost can be avoided.
In the webbing take-up device according to the fourth aspect of the present invention, when the webbing take-up device is switched from the ELR mode to the ALR mode, by unwinding an entire amount of the webbing again after taking up a predetermined amount of the webbing from the state in which the entire amount of the webbing is unwound, a one predetermined end portion of the guide groove of the cam member interlocking with the take-up shaft presses the guide pin to rotate the disc control. With this rotation of the disc control, the ALR pawl is moved from the braking operational portion to be placed on the cam member. Moreover, by taking up webbing again from this state in which the entire amount of the webbing has been unwound, the cam member rotates and disengages from the ALR pawl. As a result, the mode of the webbing take-up device is switched from the mode of use for ELR to ALR in which the ALR pawl engages with the locking wheel to prevent the same from rotating.
In the webbing take-up device according to the fourth aspect of the present invention, the switching from the ELR mode to the ALR mode is achieved by conducting the respective unwinding and taking-up operations of the webbing twice in sequential order. Accordingly, unless the aforementioned switching is carried out by the conscious volition of the vehicle occupant, an unintended and unnecessary switching from the ELR mode to the ALR mode which may make the vehicle occupant feel unpleasant does not happen.
Further, as a result, it is not necessary to set the overall length of the webbing to be much longer than the length ordinarily required to harness the vehicle occupant. Therefore, increases in size and cost can be avoided.